This invention relates to the treatment of liquids, and more particularly to water filters that are precoated by replaceable powders.
Liquid filters that produce the ultra pure water required from steam generation of electricity are commonly precoated with diatomaceous earth or powdered ion exchange resins. Such filters may have five hundred or more individual filter elements that are each over six feet in length. Full utilization of the liquid treating capacity of the precoat materials requires that the precoat be uniformly applied over the full length of each filter element. When the steam used for electric power generation comes from a nuclear reactor, the filtering apparatus becomes highly radioactive, and the individual filter elements must be capable of being installed and removed from a remote location. During prolonged usage, the dimensions of the individual filter elements may change, as for example when a wound nylon filter element shrinks during high temperature service.